MAINTAINERS: Update target git tree URL

Signed-off-by: Nicholas Bellinger <[e-mail]>

MAINTAINERS

···
 L:	[e-mail]
 L:	http://groups.google.com/group/linux-iscsi-target-dev
 W:	http://www.linux-iscsi.org
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/nab/lio-core.git master
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending.git master
 S:	Supported
 F:	drivers/target/
 F:	include/target/